A pension bill for District of Columbia employes that would reduce the federal share of funding from 100 percent to 75 percent is nearing agreement in Congress.

Only minor differences remain to be resolved in conference of a bill amended on the House floor by voice vote Monday that would reduce the federal cost of financing pensions of city police, firefighters, teachers and judges from $1.4 billion to $1.1 million over the next 25 years.

The compromise was proposed by House District Committee Chairman Ronald V. Dellums (D-Cal.) because a version of the legislation approved by Congress last year was pocket-vetoed by President Carter in November.

Mayor Marion S. Barry, testifying before the District Committee last May, urged the U.S. to add another $600 million to the package, saying the federal government should be responsible for all pensions liberally bestowed by it before the city got home rule in 1975.

The compromise agreed to this week cut the federal share of those costs to three-fourths of the benefits. The city earlier had agreed to pick up that portion of disability benefits being paid to retirees that are higher than the national average.

One reason Carter gave for vetoing last year's bill was the inordinate number of police officers and firefighters who have retired on disability from city departments here. The mayor promised this year to "fully remedy retirement abuses."

Dellums said he had been in close contact with officials of the Office of Management and Budget, who indicated that "a reduction in the federal cost of the bill would be necessary."

The necessity of compromising the committee's proposal to win OMB approval was sharply criticized in a floor speech by Rep. Stewart B. McKinney (R-Conn.), who said "We have given in to them [OMB]."

McKinney, ranking minority leader of the District Committee, said the delay caused by last November's pocket veto "cost us $150 million to $180 million." McKinney said it is "gross stupidity and arrogance of these people [OMB] to tell this body and the Senate what to do."

The final bill "represents a crude compromise with this marvelous fifth wheel of government," which McKinney described as employes of OMB -- which he derisively referred to as "the office of policy, the office of determination, the office of arrogance."

Dellums noted that this year's bill is the product of seven years of hearings and previous votes. The problem of inadequately funded pensions for District of Columbia workers was raised in 1972, when the Nelsen Commission warned that the $1 billion-plus unfunded liability would cause a financial crisis for the city.

The city now pays pension benefits out of current taxes, a burden that results in expenses of 52 cents for pensions for every $1 in current services. Unless the retirement reform bill is passed, in 20 years, according to Dellums, the cost of pensions will equal and then surpass the cost of all other spending by the city.

The solution proposed by Congress is for the city to begin setting aside for the next 20 years a fund so that a large part of retirement benefits in the 21st century can be paid from interest earned on investments of the pension fund. The big question has been how much the federal government should contribute to that fund.